Spindle bearings possibly bad?

[mtparker18]

I have an older bridgeport CNC knee mill, I don’t know what model off the top of my head.

Today I was trying to zero in my Haimer and I kept getting different readings as I was trying to zero. Upon grabbing the spindle, i noticed that I can move the haimer about .01” on the indicator (putting hand force against the spindle side to side). The machine also makes some noise upon startup, but I’m not sure if it’s bearings or not.

Anyone think that could be a bearing issue or is this actually normal?

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[Jim Dawson]

That is not good, 0.01 inch is like a mile, way too much. Time to do a bit more research. Is the problem a loose quill or is it the spindle?

Would put a long(ish) bar in the spindle where you can get some hand leverage on it and test both the quill and spindle nose to see which is moving. Then take corrective action. Hope that the problem is the spindle bearings, a loose quill is a major problem. But I have never heard of machine having a quill that loose.

[mactec54]

I have an older bridgeport CNC knee mill, I don’t know what model off the top of my head.

Today I was trying to zero in my Haimer and I kept getting different readings as I was trying to zero. Upon grabbing the spindle, i noticed that I can move the haimer about .01” on the indicator (putting hand force against the spindle side to side). The machine also makes some noise upon startup, but I’m not sure if it’s bearings or not.

Anyone think that could be a bearing issue or is this actually normal?

Try and tighten the spindle nut, this is the big round piece at the bottom of the spindle, there is an allen setscrew at the back of the spindle you have to undo this then with a pin wrench tighten the nut, then relock in the setscrew on the back, you can not over tighten this spindle nut so don't be afraid to lean on it, if you still have slop and the Bearings sound all right, then you could use a shim, this would mean to take it apart to do this, is simple as well, you just undo the Nut I just said to tighten, and then slide it all out the bottom, you would have to tilt the head to get it right out

[mtparker18]

Thanks guys. I tried to tighten the spindle nut, but the spindle keeps trying to spin while I tighten. It seems like it won't tighten anyway. I have attached a picture and video of what I'm talking about. I'm still thinking bearings...it makes some noise at startup I have noticed as well.

[Jim Dawson]

The spindle nut is the black ring directly below the shiny part. I suspect you are going to have to drop the quill out and tighten the nut on the other end. If the bearings are still good then you can get away with this. If not, maybe it's time to send the spindle out for a rebuild and get the 5 bearing mod. It cost me about $900 to get mine done and worth every penny.

[mactec54]

The spindle nut is the black ring directly below the shiny part. I suspect you are going to have to drop the quill out and tighten the nut on the other end. If the bearings are still good then you can get away with this. If not, maybe it's time to send the spindle out for a rebuild and get the 5 bearing mod. It cost me about $900 to get mine done and worth every penny.

The Black ring is the wiper, why would you send out your spindle to add 2 extra bearings, that's all they did they just remove the 2 spacers and add 2 more Bearings to take the place of the spacers, on a machine like this the extra Bearing are a waste of money

Its a big job to remove the quill on this machine, and he does not have to remove the quill to do a full Bearing job

[Jim Dawson]

The Black ring is the wiper, why would you send out your spindle to add 2 extra bearings, that's all they did they just remove the 2 spacers and add 2 more Bearings to take the place of the spacers, on a machine like this the extra Bearing are a waste of money

Its a big job to remove the quill on this machine, and he does not have to remove the quill to do a full Bearing job

Why would you not do that? I did not send my spindle out for a 5 bearing mod, I sent it out for a rebuild and had them do the 5 bearing mod while they were at it. The cost difference wasn't that much. I also had them regrind the taper.

Could I have replaced the bearings in my shop? Sure, but why? Sending it out to the pros gets it done right, in a clean room, and properly run in on the bench. I thought overall it was pretty reasonable price. A one week turnaround worked for me while I was doing some other work on the head.

I can't see enough of the machine to see what head it is, so I really couldn't comment on the size of the job to drop the quill. I can have mine out in an hour or so.

[mactec54]

Thanks guys. I tried to tighten the spindle nut, but the spindle keeps trying to spin while I tighten. It seems like it won't tighten anyway. I have attached a picture and video of what I'm talking about. I'm still thinking bearings...it makes some noise at startup I have noticed as well.

The noise at startup would be the Vari-Drive needing some work, if it was the Bearings making noise at startup then it would be there all the time

Tightening the spindle bearing Nut, has nothing to do with the spindle moving, so I'm not sure what part is turning when you do the Nut up on the bottom of the quill ,the Quill should not be able to turn

On the front of the quill housing, remove the cover where the micro switches are, there is a block mounted onto the Quill this should stop the quill from turning, you have a lot of problems if this is missing

[mactec54]

Why would you not do that? I did not send my spindle out for a 5 bearing mod, I sent it out for a rebuild and had them do the 5 bearing mod while they were at it. The cost difference wasn't that much. I also had them regrind the taper.

Could I have replaced the bearings in my shop? Sure, but why? Sending it out to the pros gets it done right, in a clean room, and properly run in on the bench. I thought overall it was pretty reasonable price. A one week turnaround worked for me while I was doing some other work on the head.

I can't see enough of the machine to see what head it is, so I really couldn't comment on the size of the job to drop the quill. I can have mine out in an hour or so.

The photo tells it all, if you know your machines, this has a Ballscrew mounted on top of the Quill and is a major job to take everything apart, for someone that has not done a complete rebuild of one of these machines before

[mtparker18]

Thanks for the info guys. I have attached a picture of my machine, hopefully you can tell me which head I have, as I'm unsure. I am pretty mechanically inclined, I just haven't touched a BP head before. Is there a service manual or something I can buy that will walk me through rebuild?

[mactec54]

Thanks for the info guys. I have attached a picture of my machine, hopefully you can tell me which head I have, as I'm unsure. I am pretty mechanically inclined, I just haven't touched a BP head before. Is there a service manual or something I can buy that will walk me through rebuild?

It is a series I Ridged Ram, Boss series cnc, can't tell by the photo what Boss model it is, you can get closer by looking at the timing pulleys on the Y axes to see if they are 1:1 or 2:1, you would have to search the web or sometimes they are on Ebay for a manual, yours has been retro fitted with the control and different motors so they may have changed the timing pulleys as well, so that may not tell use what model you have, there is a machine number on the front of the Knee this to may help to get the right model Boss

[seanano]

That gear shifter looks like the one on my R2E4 head. It is offset to the side and forward for the big plastic shrouds used on the later machines (R2E3 looks similar from online pictures, not sure though as my R2E3 doesn't have a head). Regardless, here is a maintenance manual for an R2E4:

Bridgeport ==> BOSS ==> R2E4

It does have a section on the head which may be sufficient even if yours isn't exactly the same (a lot of parts appear to be common across the BOSS rigid ram heads). A word of warning about the manual, I noticed some numbers that were obviously incorrect (7 which should have been a 1) so double check any critical values.

[mactec54]

That gear shifter looks like the one on my R2E4 head. It is offset to the side and forward for the big plastic shrouds used on the later machines (R2E3 looks similar from online pictures, not sure though as my R2E3 doesn't have a head). Regardless, here is a maintenance manual for an R2E4:

Bridgeport ==> BOSS ==> R2E4

It does have a section on the head which may be sufficient even if yours isn't exactly the same (a lot of parts appear to be common across the BOSS rigid ram heads). A word of warning about the manual, I noticed some numbers that were obviously incorrect (7 which should have been a 1) so double check any critical values.

Yes that will work for him the R2E3 Head has almost all the same parts, all the major parts are the same so if he starts at Chapter 11 he should be able to figure it out, they are not very hard to do

[mtparker18]

Thanks for the info guys. I will look over that manual more in depth, although I might just find someone in my area who can service my machine and get it over with instead. It looks pretty simple as I am very mechanically inclined, but I'm afraid of messing something up.